Abstract

A novel six-port optical reflectometer is proposed and demonstrated to measure the complex reflection coefficients of an optical component, such as an optical waveguide or a phase-conjugate mirror. This simple reflectometer architecture is composed of two cascaded Michelson interferometers. By using a scattering-matrix representation, it is found that the reflection coefficients to be measured must satisfy the three-cycle (performance) equations. For an optical implementation, adjustable high-quality mirrors mounted on microtranslation stages are needed to obtain a suitable phase relationship between two Michelson interferometers. A system calibration is also needed before a measurement, to determine the performance-equation parameters. After this calibration, by simply measuring the output optical power at the various reflectometer ports, the reflection coefficients of unknown optical components can be computed. In our experiment, two λ/10 (λ = 633 nm) mirrors were mounted on computer-controlled micropositioners and were placed at two of the six reflectometer ports. A λ/2 phase shift between the two interferometers was selected. Detailed descriptions of the reflectometer's model, its optical implementation, and preliminary experimental results will be presented.

© 1990 Optical Society of America